Miniature indexing mechanism

ABSTRACT

A miniature indexing mechanism employs a shaft of a first diameter having a drum of a second diameter, the second diameter being larger than the first. Two holes are located diametrically opposite each other in the walls of the drum. A hat shaped housing member includes a plurality of smaller holes circumferentially located along the inner wall thereof and has an internal diameter slightly larger than the drum section of the shaft such that the drum section is free to rotate within the wall of the housing member. Ball bearings are inserted in each of the two drum holes and are biased outwardly toward the inner walls of the housing member by a circular leaf spring. As the shaft is rotated, the bearings seat in the holes along the inner walls of the housing thus providing an indexing mechanism.

United States Patent Hatman MINIATURE INDEXING MECHANISM Lewandowski eta1 ..74/527 X 14kg] i [45] July 18, 1972 Primary Examiner-Milton KaufmanAttomey-Norman J. O'Malley, Elmer J. Nealon and Robert T. Orner [57]ABSTRACT A miniature indexing mechanism employs a shafi of a firstdiameter having a drum of a second diameter, the second diameter beinglarger than the first. Two holes are located diametrically opposite eachother in the walls of the drum. A hat shaped housing member includes aplurality of smaller holes circumferentially located along the innerwall thereof and has an internal diameter slightly larger than the drumsection of the shaft such that the drum section is free to rotate withinthe wall of the housing member. Ball bearings are insorted in each ofthe two drum holes and are biased outwardly toward the inner walls ofthe housing member by a circular leaf spring. As the shaft is rotated,the bearings seat in the holes along the inner walls of the housing thusproviding an indexing mechanism.

8 Clains, 4 Drawing Figures PATENTED JULI 81972.

INVENTOR.

RAYMOND 6. HARTMAN QZM 70 ATTORNEY MINIATURE INDEXING MECHANISMBACKGROUND OF THE INVENTION This invention relates to indexingmechanisms and in particular to a miniature indexing mechanism useful ina rotatable switching device in which discrete switch positions aredesired.

In small portable electronic devices, such as a small handheld rescueradio employing a plurality of radio channels and functions, there is arequirement for a miniature switch which has discrete positionscorresponding to each channel and/or function. Existing detents orindexing mechanisms are generally too large and bulky. For example,standard mechanisms have a ball retainer mounted on a rotating shaft, aplurality of indexing cams located in a housing surrounding the shaftand ball retainer. Helical springs exert force on the balls, seatingthem in detents within the housing. Separate shaft alignment bearingsand load bearings are required to center the rotating shaft within thehousing.

It would therefore be advantageous to have and it is one of the objectsof this invention to provide a miniature detent mechanism employing asimple design for attaining shaft alignment and discrete shaftpositions.

SUMMARY OF THE INVENTION An indexing mechanism according to the presentinvention includes a shaft having a first diameter and an open-endeddrum section coaxial with the longitudinal axis of the remainder of theshaft. The drum section, having a larger diameter than the firstdiameter, includes an opening in the wall thereof. A housing member hasa hollow cylindrically shaped interior with first and second openings inthe respective ends thereof, the diameter of the first opening beingslightly larger than the first diameter of the shaft and the diameter ofthe second opening being slightly larger than the diameter of the drumsection. The hollow cylindrically shaped interior includes a pluralityof indentations located circumferentially around the wall thereof, thesize of each of the indentations being slightly less than the size ofthe opening in the wall of the drum section of the shaft.

The shaft is positioned within the housing member such that the drumsection rotates within the hollow cylindrically shaped interior of thehousing member. A bearing member is positioned in the opening in thewall of the drum section of the shaft and is forced into a certain oneof the plurality of indentations in the interior of the housing memberby a biasing means. As the shaft is rotated, the bearing member rides inand out the indentations in the housing member thus providing anindexing mechanism.

DESCRIPTION OF THE DRAWINGS The construction and operation of the detentmechanism will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a partial cross-sectional view of an embodiment of the detentmechanism according to the invention;

FIG. 2 is a perspective view of a shaft employed in the embodiment ofFIG. 1;

FIG. 3 is a perspective view of a housing member employed in theembodiment of FIG. 1; and

FIG. 4 is a perspective view of a spring employed in the embodiment ofFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION An indexing mechanism 10, across-sectional view of which is shown in FIG. 1, includes a shaft 12(FIG. 2) having a first diameter D, and a hollow drum section 14 havinga second diameter D,. Included in the wall of the drum 14 is a pair ofopenings 16 located diametrically opposite each other. The function ofthe openings 16 will be discussed hereinafter. Also included in theindexing mechanism is a hat shaped housing 18 having a cylindricallyshaped inner wall 20 with first and second circular openings 22 and 24in the ends thereof. The diameter of the first opening 22 is slightlylarger than the first diameter D, of the shaft 12, and the diameter ofthe second opening 24 is slightly larger than the diameter D, of thedrum 14. Located circumferentially along the inner wall 20 is aplurality of indentations, for example, holes 26, the function of whichwill be explained hereinbelow. The diameter of each of the holes 26 isless than the size of the openings 16 of the drum [4.

As shown in FIG. 1, the shaft 12 is positioned in the housing 18 suchthat the drum 14 is located within the cylindrically shaped inner wall20 and the openings 16 of the drum 14 are in radial alignment with theplurality of holes 26. (Note that surface 30, associated with theopening 22 of the housing member 18, and the surface of the inner wall20 act as shaft alignment bearings for the shaft 12.)

Bearings, such as the ball bearings 32, are located within the openings16 of the drum 14 which forms a race for the ball bearings 32. Acollar-like leaf spring 34 (FIG. 4) is located within the drum l4 andexerts a radially outward force against the ball bearings 32 causingthem to seat into certain ones of the holes 26 as the shaft is turned. Apin 54 on the inner wall of the drum 14 projects into the opening 56 ofthe spring 34 to prevent the spring 34 from rotating relative to thedrum 14.

It is to be appreciated that the leaf spring 34 and the ball bearings 32are positioned on the drum 14 before the shaft 12 is placed in thehousing 18. To prevent longitudinal travel of the shaft 12 with respectto the housing 18, the shaft 12 includes two circumferential channels 38and 40 in which clip springs 42 and 44, respectively, are inserted. Awasher 46 is sandwiched between the clip spring 40 and the base 48 ofthe housing 18 to limit the longitudinal travel of the shaft 12. A knob(nOt shown) can be mounted on a flat section 50 of the shaft tofacilitate turning.

While there has been shown and described what is considered a preferredembodiment of the present invention, various modifications and changesmay be made therein without departing from the invention as defined inthe appended claims.

What is claimed is:

1. An indexing mechanism comprising:

a shaft having a first diameter and including a drum section coaxialwith the longitudinal axis of said shaft, said drum section having anopen end and an opening in the wall thereof, the diameter of said drumsection being larger than said first diameter;

a housing member having a hollow cylindrically shaped interior withfirst and second openings in the respective ends thereof, the diameterof said first opening being slightly larger than the first diameter ofsaid shaft, and the diameter of said second opening being slightlylarger than the diameter of said drum section of said shaft, said hollowcylindrically shaped interior including a plurality of indentationslocated circumferentially around the wall thereof, the size of each ofsaid plurality of indentations being slightly less than the size of theopenings in the walls of said drum section,

said shaft being positioned in said housing member such that the drumsection rotates within the hollow cylindrically shaped interior of saidhousing member;

a bearing member positioned in the opening in the wall of the drumsection of said shaft; and

biasing means positioned within the drum section and exert ing a forceon said bearing member in a direction towards said housing member.

2. An indexing mechanism comprising:

a shaft having a first diameter and including a drum section coaxialwith the longitudinal axis of said shaft, said drum section having anopen end and a pair of openings in the wall thereof, the diameter ofsaid drum section being larger than said first diameter;

a housing member having a hollow cylindrically shaped interior withfirst and second openings in the respective ends thereof, the diameterof said first opening being slightly larger than the first diameter ofsaid shaft and the diameter of said second opening being slightly largerthan the diameter of said drum section of said shaft, said hollowcylindrically shaped interior including a plurality of indentationslocated circumferentially around the wall thereof, the size of each ofsaid plurality of indentations being slightly less than the size of theopenings in the wall of said drum section,

said shaft being positioned in said housing member such that the drumsection rotates within the hollow cylindrically shaped interior of saidhousing member;

bearing members each positioned in one of the openings in the wall ofthe drum section of said shaft; and

biasing means positioned within the drum section and exerting a force onsaid bearing members in a direction towards said housing member.

3. An indexing mechanism according to claim 2 including means forlimiting the longitudinal travel of said shaft with respect to saidhousing member.

4. An indexing mechanism according to claim 3 wherein:

said shaft has a circumferential channel adjacent to each end of saidhousing member; and

said means for limiting includes:

a clip spring positioned in each of said circumferential channels andhaving a surface larger than the first diameter of said shaft, and

a washer having a circular void, the diameter of which is slightlylarger than said first diameter of said shaft, said washer having anoverall diameter greater than the diameter of the second diameter ofsaid housing member and being sandwiched between said housing member andone of said clip springs.

5. An indexing mechanism according to claim 2 wherein said biasing meansincludes a collar-like leaf spring, the expanded diameter of which islarger than the diameter of the wall of the drum section of said shaftthus causing a radially outward force on said bearing members whencompressed in the drum section of said shaft.

6. An indexing mechanism according to claim 2 wherein:

said bearing members are ball bearings;

the diameter of the pair of openings in the walls of said drum sectionis slightly larger than the diameter of said bearings; and

the indentations of said housing member are circular openings having adiameter less than the diameter of said ball bearings.

7. An indexing mechanism according to claim 6 wherein the diameter ofsaid ball bearings is larger than the thickness of the wall of saiddrum.

8. An indexing mechanism according to claim 7 wherein the walls of saiddrum have the openings located diametrically op posite each other.

l i t 22 3 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION IPatent No. 3,677,096 Datedr July 18, 1972 Inventor(s) Raymond G. Hartmen It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In the heading (Item [72] Inventor the inventor should be Raymond G.Hartman-. I

At column 2, line 35, "nOt" should be --not-'-.

Signed and sealed this 26th day of December 1972..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of PatentsAttesting Officer

1. An indexing mechanism comprising: a shaft having a first diameter andincluding a drum section coaxial with the longitudinal axis of saidshaft, said drum section having an open end and an opening in the wallthereof, the diameter of said drum section being larger than said firstdiameter; a housing member having a hollow cylindrically shaped interiorwith first and second openings in the respective ends thereof, thediameter of said first opening being slightly larger than the firstdiameter of said shaft, and the diameter of said second opening beingslightly larger than the diameter of said drum section of said shaft,said hollow cylindrically shaped interioR including a plurality ofindentations located circumferentially around the wall thereof, the sizeof each of said plurality of indentations being slightly less than thesize of the openings in the walls of said drum section, said shaft beingpositioned in said housing member such that the drum section rotateswithin the hollow cylindrically shaped interior of said housing member;a bearing member positioned in the opening in the wall of the drumsection of said shaft; and biasing means positioned within the drumsection and exerting a force on said bearing member in a directiontowards said housing member.
 2. An indexing mechanism comprising: ashaft having a first diameter and including a drum section coaxial withthe longitudinal axis of said shaft, said drum section having an openend and a pair of openings in the wall thereof, the diameter of saiddrum section being larger than said first diameter; a housing memberhaving a hollow cylindrically shaped interior with first and secondopenings in the respective ends thereof, the diameter of said firstopening being slightly larger than the first diameter of said shaft andthe diameter of said second opening being slightly larger than thediameter of said drum section of said shaft, said hollow cylindricallyshaped interior including a plurality of indentations locatedcircumferentially around the wall thereof, the size of each of saidplurality of indentations being slightly less than the size of theopenings in the wall of said drum section, said shaft being positionedin said housing member such that the drum section rotates within thehollow cylindrically shaped interior of said housing member; bearingmembers each positioned in one of the openings in the wall of the drumsection of said shaft; and biasing means positioned within the drumsection and exerting a force on said bearing members in a directiontowards said housing member.
 3. An indexing mechanism according to claim2 including means for limiting the longitudinal travel of said shaftwith respect to said housing member.
 4. An indexing mechanism accordingto claim 3 wherein: said shaft has a circumferential channel adjacent toeach end of said housing member; and said means for limiting includes: aclip spring positioned in each of said circumferential channels andhaving a surface larger than the first diameter of said shaft, and awasher having a circular void, the diameter of which is slightly largerthan said first diameter of said shaft, said washer having an overalldiameter greater than the diameter of the second diameter of saidhousing member and being sandwiched between said housing member and oneof said clip springs.
 5. An indexing mechanism according to claim 2wherein said biasing means includes a collar-like leaf spring, theexpanded diameter of which is larger than the diameter of the wall ofthe drum section of said shaft thus causing a radially outward force onsaid bearing members when compressed in the drum section of said shaft.6. An indexing mechanism according to claim 2 wherein: said bearingmembers are ball bearings; the diameter of the pair of openings in thewalls of said drum section is slightly larger than the diameter of saidbearings; and the indentations of said housing member are circularopenings having a diameter less than the diameter of said ball bearings.7. An indexing mechanism according to claim 6 wherein the diameter ofsaid ball bearings is larger than the thickness of the wall of saiddrum.
 8. An indexing mechanism according to claim 7 wherein the walls ofsaid drum have the openings located diametrically opposite each other.